Methods and compositions for targeting fenestrated vasculature

ABSTRACT

Targeting of a fenestrated vasculature at a body site by micro or nanoparticles can be increased by using particles that have a radius substantially equal to a critical radius of a normal vasculature at the body site. The particles can be used for treating or monitoring a physiological condition responsible for the fenestrated vasculature. A method of improving an ability of micro or nanoparticles to target fenestrated blood vessels in a body site by selecting particles from a population of the micro or nanoparticles, where the selected particles have a radius that permits enhanced delivery into the fenestrated blood vessels.

BACKGROUND

1. Field of the Invention

The present application relates generally to compositions and methodsutilizing micro and nanoparticles for delivery of active agents, such astherapeutic or imaging agents, and more particularly to compositions andmethods utilizing micro and nanoparticles for targeting fenestratedendothelium of blood vessels and for treating and monitoring aphysiological condition responsible for the fenestrated endothelium.

2. Description of Related Art

Nano and microscale particles, also known as nanovectors, can be usedfor delivery of active agents, such as therapeutic or imaging agents,see e.g. Ferrari, M. Nat. Rev. Cancer 5:161, 2005. Illustrative examplesof such nanovectors include silicon particles, see, e.g., Cohen, M. H.,K. Melnik, A. Boiasrki, M. Ferrari, F. J. Martin. Biomed. Microdevices5:253-259, 2003, polymer-based particles, see, e.g., Duncan, Nat.Rev./Drug Discov. 2:347-360, 2003; quantum dots, see e.g. Alivisatos, P.Science 271:933-937, 1996; iron oxide particles, see, e.g., Winter, P.M., S. A. Wickline, and G. M. Lanza. Cancer Res. 63:5838-5843, 2003;gadolinium-containing particles, see e.g. Oyewumi, M. O., and R. J.Mumper. J. Control. Release 24:613-626, 2004; gold nanoshells, see,e.g., Goldsmith, H. L., and V. T. Turitto. Thromb. Haemost. 55:415-435,1986 and low-density lipid particulates, see, e.g., Bloch, S. H., M.Wan, P. A. Dayton, and K. W. Ferrara. Appl. Phys. Lett. 84(4):631-633,2004.

Physiological conditions such as tumor or inflammation can result information of fenestrations in endothelium of blood vessels. To treat ormonitor such physiological conditions micro or nanoparticles should beable to reach the blood vessels affected by the fenestrations.Accordingly, a need exists to develop particles that can effectivelytarget the fenestrated blood vessels, i.e., blood vessels havingfenestrations in their endothelium due to a physiological condition suchas tumor or inflammation.

SUMMARY

In accordance with certain embodiments of the present invention, amethod is provided for targeting fenestrated blood vessels in a bodysite, comprising administering to a subject in need thereof acomposition comprising particles having a radius that permits enhanceddelivery into fenestrated blood vessels of the body site, wherein theparticles comprise at least one active agent. In some embodiments, theat least one active agent comprises a therapeutic agent. In someembodiments, the therapeutic agent is an anticancer agent. In someembodiments, the active agent comprises an imaging agent.

In some embodiments, the particles comprise a nanoporous material, suchas, for example, a nanoporous silicon, a nanoporous oxide material, or ananoporous silicon dioxide.

In certain other embodiments, the particles comprise a biodegradablematerial.

In some embodiments, the particles comprise at least one recognitionmoiety disposed on a surface of each of the particles. In certainembodiments, the at least one recognition moiety comprises arenormalized vasculature recognition moiety. In certain embodiments, theat least one recognition moiety comprises a coopted vasculaturerecognition moiety. In certain embodiments, the at least one recognitionmoiety comprises an angiogenesis vasculature recognition moiety. Incertain embodiments, a recognition moiety comprises hydrophilic polymerchains.

In some embodiments, one or more of said particles are selected from thegroup consisting of liposomes, fullerene nanoparticles, semiconductornanoparticles and metal nanoparticles.

In some embodiments, an above-described method comprises fabricating oneor more of said particles. For example, such fabricating may comprisefabricating by a top-down technique.

In some embodiments of an above-described method, administeringcomprises injecting the composition intravascularly into the subject,e.g., in a vasculature of the body site.

In certain embodiments of an above-described method, the subject is amammal, preferably a human. The body site may be brain, skin, skeletalmuscle, lung, heart, kidney, stomach, or intestine, for example.

The composition employed in an above-described method comprises asuspension of the particles, in some embodiments.

A condition responsible for the fenestrated blood vessel condition maybe a tumor, for instance, and in some embodiments of an above-describedmethod, the method includes administering to the subject a vasculaturenormalizing agent.

Also provided in accordance with certain embodiments of the presentinvention is a method of improving efficacy of a composition thatcomprises particles that contain at least one active agent. This methodcomprises selecting a second population of particles from a firstpopulation of micro or nanoparticles, such that the particles in thesecond population have a radius that permits enhanced delivery intofenestrated blood vessels of a target body site. The method furthercomprises forming a composition comprising the selected secondpopulation of particles. In certain embodiments, the selected particlesconstitute at least 10% of the first particles by number. In certainembodiments, the selected particles constitute at least 20% of the firstparticles by number. In certain embodiments, the selected particlesconstitute at least 50% of the first particles by number. In certainembodiments, the selected particles constitute at least 80% of the firstparticles by number.

Still other embodiments of the present invention provide a method ofimproving the ability of micro or nanoparticles to target fenestratedblood vessels in a body site by selecting particles from a population ofthe micro or nanoparticles, where the selected particles have a radiusthat facilitates or permits enhanced delivery into the fenestrated bloodvessels. These and other embodiments, features and advantages will beapparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE schematically depicts blood vessels of the circulatorysystem.

DETAILED DESCRIPTION Definitions

Unless otherwise specified “a” or “an” means one or more.

The term “critical radius” refers to a critical radius of a normalnon-fenestrated blood vessel, at a particular body site, which isdefined below.

“Recognition moiety” can be any factor that can facilitate targeting ofa specific site by a particle. The recognition moiety can be a chemicaltargeting moiety, a physical targeting moiety or a combination thereof.The chemical targeting moiety can be a chemical group or molecule on asurface of the particle; the physical targeting moiety can be a specificphysical property of the particle such as a surface such orhydrophobicity.

“Microparticle” means a particle having a maximum characteristic sizefrom 1 micron to 1000 microns, or from 1 micron to 100 microns.“Nanoparticle” means a particle having a maximum characteristic size ofless than 1 micron.

“Body site” means a part of a body of a subject that has blood vessels.Body site can be an organ in a body of a subject such as brain, heart,kidney, skin, lung, muscle, stomach or intestine.

“Fenestrated blood vessel” refers to a blood vessel that has afenestrated endothelium. caused by a physiological condition, such as atumor or inflammation, but the term “fenestrated blood vessel” excludesblood vessels that normally have a fenestrated endothelium such as, forexample, capillaries of the gastrointestinal tract, capillaries ofglomerulus in kidney or sinusoids in the bone marrow. Fenestrated bloodvessel further means a blood vessel having a hydraulic permeabilityhigher than a normal blood vessel. Characteristic values of hydraulicpermeabilities L_(p) for capillaries in selected body sites in a humanbody are presented, for example, in Ganong, W. F. Review of MedicalPhysiology, 21st ed. New York: Lange Medical Books/McGraw-Hill, MedicalPublishing Division, 2003, as summarized in Table 1.

TABLE 1 Hydraulic permeability Organ L_(p), μm/Pa s Brain 3 Skin 100Skeletal muscle 250 Lung 340 Heart 860

The present disclosure incorporates herein by reference in its entiretyP. Decuzzi, F. Causa, M. Ferrari and P. A. Netti “The Effectivedispersion of Nanovectors Within the Tumor Microvasculature,” Annals ofBiomedical Engineering, 34(4): 633-641, 2006.

The inventors have recognized that an effective diffusivity offenestrated blood vessels, such as fenestrated capillaries, is lowerthan an effective diffusivity of normal blood vessels, such as normalcapillaries, at the same body site. Thus, for a given size, particles,such as nanovectors, tend to reach the normal blood vessels in largernumbers than the fenestrated blood vessels.

The inventors have also recognized that, for a particular blood vessel,there is a critical radius of a particle, for which an effectivediffusivity of particles has a minimum. Such a critical radius can existfor both fenestrated blood vessels and normal blood vessels. Thecritical radius for normal vessels is usually smaller than the criticalradius for fenestrated vessels at the same body site.

The inventors have determined that administration of particles having aradius that is substantially equal to a critical radius for a normalblood vessel at a body site can increase a number of particles reachinga fenestrated blood vessel at the body site.

Accordingly, in one embodiment, the invention provides a method oftargeting one or more fenestrated blood vessels in a body site of asubject, preferably a mammal and more preferably a human, in needthereof by administering to the subject a composition comprisingparticles with a radius substantially equal to a critical radius for thebody site, wherein the particles comprise at least one active agent. Thecomposition can also comprise additional particles, i.e., particles thatdo not have a radius substantially equal to the critical radius for thebody site. In various embodiments, the particles with a radiussubstantially equal to the critical radius for the body site canconstitute at least 10%, or at least 25%, or at least 50%, or at least75%, or at least 90% by number of all the particles in the composition.

In one embodiment, the at least one active agent comprises a therapeuticagent and thus the method of targeting a fenestrated vasculature is usedfor treating a physiological condition responsible for the fenestratedvasculature. In another embodiment, the at least one active agentcomprises an imaging agent and the method of targeting a fenestratedvasculature can be used for monitoring a physiological conditionresponsible for the fenestrated vasculature. In still anotherembodiment, the at least one active agent comprises both an imagingagent and a therapeutic agent and the method of targeting a fenestratedvasculature is used for both monitoring and treating a physiologicalcondition responsible for the fenestrated vasculature.

In another embodiment, the invention provides a method of improvingtargeting of particles to fenestrated vasculature in a body site byselecting particles from a population of the particles according totheir size (e.g., radius) such that a relative amount of the selectedparticles having a size that permits enhanced delivery to thefenestrated vasculature of the body site. The selected particlespreferably have a radius substantially equal to a critical radius forthe body site. Selecting of the particles according to their size can beperformed, for example, using Zetasizer™ Nano series instrument fromMalvern Instruments, Worcestershire, United Kingdom. The relative amountof the selected particles is preferably at least 10%, or at least 25%,or at least 50%, or at least 75%, or at least 90% by number in the finalproduct. Upon selecting the particles according to their size, acomposition is formed from the selected particles. Such a composition ismore effective for targeting the fenestrated vasculature at the bodysite than a composition formed from the starting population of theparticles. When the particles comprise a therapeutic agent, thecomposition with an increased relative amount of the selected particlescan reduce the overall dosage of the therapeutic agent in thecomposition for effective treatment of a physiological conditionresponsible for the fenestrated vasculature at the body side compared toan unselected composition, i.e., a composition formed from an unselectedpopulation of the particles. Similarly, when the particles comprise animaging agent, the composition enriched with the selected particles canreduce the amount of the particles for monitoring a physiologicalcondition responsible for the fenestrated vasculature at the body sitecompared to the unselected composition.

Critical Radius

Preferably, a critical radius for a normal non-fenestrated blood vesselis determined using the following formula:

$a_{cr} = {\frac{2}{\pi \sqrt{3}}\frac{k_{B}T}{\eta \; {RU}}}$

where k_(B) is Boltzmann constant, T is an absolute temperature of theblood expressed in Kelvins; R is a radius of the blood vessel; U is ablood velocity in the blood vessel, η is a viscosity of the blood.

For the blood viscosity one preferably uses an average value of 10⁻³ Pas for a human, or alternatively, one can determine a value of the bloodviscosity experimentally. For example, a value of the blood viscosity isevaluated from a plasma viscosity determined with a glass capillaryviscometer, hematocrit and mean wall share rate as disclosed in WeaverJ. P. et al. Clin. Sci. 36: 1-10, 1969 and Dammers R., et al. J. Appl.Physiol. 94:485-489, 2003, which are both incorporated herein byreference in their entirety.

For the blood velocity in the blood vessel and the radius of the bloodvessel, one preferably uses values summarized in Table 2 as taken fromGanong, W. F. Review of Medical Physiology, 21st ed. New York: LangeMedical Books/McGraw-Hill Medical Publishing Division, 2003,incorporated herein by reference in its entirety. The FIGUREschematically depicts blood vessels of the circulatory system.

TABLE 2 Blood vessel U, μm/s R_(e), μm Aorta 4 × 10⁵ 25 × 10³ Artery 1 ×10⁵  4 × 10³ Arteriole 5 × 10³ 20-50 Capillary 10-100  5-10 Venules 5 ×10² 20-50 Vein 5 × 10⁴ 2-5 × 10³  Vena cava 1 × 10⁵ 30 × 10³

Alternatively, one can determine the blood velocity and the radius ofthe blood vessel experimentally using, for example, an ultrasoundsystem, such as Ultramark 9 plus™, Advanced

Technology Laboratories, Bellevue, Wash. as detailed in Dammers R., etal. J. Appl. Physiol. 94:485-489, 2003. In this case, the blood velocitycan be a mean center velocity averaged over a heart cycle.

Because, for a particular body site, there can be a plurality of bloodvessels of the same type, one can use values of the blood velocity andthe radius averaged over such blood vessels, when calculating thecritical radius for the body site.

As the fenestrations associated with a physiological condition, such asa tumor or inflammation, usually affect smaller blood vessels of thebody site, such as capillaries, the critical radius for the body site isusually a critical radius for normal capillaries of the body site. Acritical radius can be calculated for any type of a blood vessel,however.

When estimating a critical radius for a body site, one can optionallyfurther take into account permeability of blood vessels as follows:

${a_{cr} = {\frac{2}{\pi \sqrt{3}}\frac{k_{B}T}{\eta \; {RU}}{\int_{0}^{1}\frac{\overset{\sim}{z}}{f\left( {\Omega,\Pi,\overset{\sim}{z}} \right)}}}},\ {where}$${f\left( {\Omega,\Pi,\overset{\sim}{z}} \right)} = \left\lbrack {\frac{\left( {1 + ^{2\overset{\sim}{z}\; \Pi}} \right) - {{^{\Pi}\left( {1 + ^{2{({\overset{\sim}{z} - 1})}\Pi}} \right)}\Omega}}{2 - {{^{\Pi}\left( {1 + ^{{- 2}\Pi}} \right)}\Omega}}^{{- \Pi}\overset{\sim}{z}}} \right\rbrack^{2}$or${{f\left( {\Omega,\Pi,\overset{\sim}{z}} \right)} = \left\lbrack {1 + {{\overset{\sim}{z}\left\lbrack {{2\Omega} + {\left( {1 - \Omega} \right)\overset{\sim}{z}}} \right\rbrack}\frac{\Pi^{2}}{\Omega - 1}}} \right\rbrack^{- 1}},$

In the above formula,

${\Pi = {\frac{4l}{R}\sqrt{\frac{\eta}{R}L_{p}}}},{\Omega = \frac{p_{art} - \pi_{int}}{p_{ven} - \pi_{int}}},$

where l is a length of a blood vessel such as a capillary; p_(art), evenand π_(int) are respectively a blood pressure at the arterial side ofcapillary, a blood pressure at the venous side of capillary andinterstitial fluid pressure in the capillary. The integration in theabove formula can be performed either analytically or numerically using,for example, standard software programs.

L_(p) is a permeability of a blood vessel, see, e.g., Table 1.

l, an average length of capillaries for a particular body site can beobtained using histological inspections as known to those of ordinaryskill in the art.

p_(art) and p_(ven), blood pressures at the arterial and venous sides ofcapillaries for a particular body site, can be obtained, for example,using catherers immersed in corresponding arterial and venous bloodvessels fluidically connected to the capillaries at the body site.π_(int), an interstitial fluid pressure, can be typically considered tobe zero for normal capillaries. Still, if necessary, the interstitialfluid pressure can be measured for blood vessels using methods describedin Boucher, Y., Baxter, L. T., and Jain, R. K. (1990) InterstitialPressure Gradient in tissue-isolated and subcutaneous tumore:Implications for therapy. Cancer Res. 50, 4478-4484, incorporated hereinby reference in its entirety.

Because values of permeability L_(p) can change significantly from onebody site to another, see, e.g., Table 1, a critical radius can alsovary from organ to organ. Thus, for example, selected particles fortargeting the brain can be smaller in radius than selected particlesdelivered to the heart.

Particles

A selected particle means a particle optimized for targeting afenestrated microvasculature, i.e. one or more fenestrated bloodvessels, of a particular body site. In other words, the selectedparticles have a radius substantially equal to a critical radius of thebody site. “Substantially equal” means that the radius of the selectedparticle equals the critical radius within a certain margin. Such amargin can be determined, for example, from variations of radii andblood velocities of normal blood vessels in the body site. In someembodiments, the margin can be, for example, 30% or less, i.e., theradius of the selected particle is from 0.7 to 1.3 of the criticalradius. In various embodiments, the margin can be 20% or less, or 10% orless, or 5% or less, or 3% or less, or 1% or less.

A selected particle can be a micro or nanoparticle of any type. Forexample, the selected particle can be a liposome, a polymer-basedparticle, a silicon-and silica based particle, a quantum dot, a goldnanoshell or a dendrimer.

Selected particles can be fabricated to have a specific radius oralternatively selected particles can be screened from a pool ofparticles having a distribution of sizes. The selection from the pool ofparticles can be performed, for example, using Zetasizer™ Nano seriesinstrument from Malvern Instruments, Worcestershire, United Kingdom,which allows measuring radii of the particles.

The selected particle can be fabricated by any suitable Method.Preferably the fabrication method provides a control over the size ofthe particle. For example, in some embodiments, the particles arefabricated by a top-down microfabrication or nanofabrication methodssuch as photolithography, electron beam lithography, X-ray lithography,deep UV lithography or nanoprint lithography. The advantage of using thetop-down fabrication methods can be that such methods provide for ascaled up production of particles that are uniform in dimensions.

In some embodiments, selected particles can have on their surfacestargeting moieties such as ligands, aptamers or antibodies. For example,ligands can be chemically linked to appropriate reactive groups on thesurface of the particles. Protein ligands can be linked to amino- andthiol-reactive groups under conditions effective to form thioether oramide bonds respectively. Methods for attaching antibody or otherpolymer binding agents to an inorganic or polymeric support aredetailed, for example, in Taylor, R., Ed., Protein ImmobilizationFundamentals and Applications, pp. 109110 (1991).

In some embodiments, the selected particle can have one or more channelsconnecting a reservoir with the surface. In some embodiments, thereservoir and the channels can be pores in the body of the particle. Insuch case, the particle can comprise a porous or nanoporous material.The pores of the porous or nanoporous material can be controlled toachieve a desired load of the active agent and a desired release rate.The nanoporous material with controllable pore size can be an oxidematerial, such as SiO₂, Al₂O₃, or TiO₂. Fabrication of nanoporous oxideparticles, also known as sol gel particles, is detailed, for example, inPaik J. A. et. al. J. Mater. Res., Vol. 17, August 2002. The nanoporousmaterial with controllable pore size can be also nanoporous silicon. Fordetails of fabrication of nanoporous silicon particles, see Cohen M. H.et. al. Biomedical Microdevices 5:3, 253-259, 2003.

In some other embodiments, the selected particle has no channels at all.Such particle can comprise, for example, a biodegradable material. Forexample, the particle may be formed of metals such as iron, titanium,gold, silver, platinum, copper, and alloys and oxides thereof. Thebiodegradable material can be also a biodegradable polymer such aspolyorthoesters, polyanhydrides, polyamides, polyalkylcyanoacrylates,polyphosphazenes, and polyesters. Exemplary biodegradable polymers aredescribed, for example, in U.S. Pat. Nos. 4,933,185, 4,888,176, and5,010,167. Specific examples of such biodegradable polymer materialsinclude poly(lactic acid), polyglycolic acid, polycaprolactone,polyhydroxybutyrate, poly(N-palmitoyl-trans-4-hydroxy-L-proline ester)and poly(DTH carbonate).

In some embodiments, the particle is an active agent per se.

Active Agent

The active agent can be a therapeutic compound or an imaging agent, forexample. The selection of the active agent depends on the desiredapplication. The therapeutic agent may be any physiologically orpharmacologically active substance that can produce a desired biologicaleffect in fenestrated vasculature of the subject, such as a mammal or ahuman. The therapeutic agent may be any inorganic or organic compound,without limitation, including peptides, proteins, nucleic acids, andsmall molecules. The therapeutic agent may be in various forms, such asan unchanged molecule, molecular complex, pharmacologically acceptablesalt, such as hydrochloride, hydrobromide, sulfate, laurate, palmitate,phosphate, nitrite, nitrate, borate, acetate, maleate, tartrate, oleate,salicylate, and the like. For acidic therapeutic agent, salts of metals,amines or organic cations, for example, quaternary ammonium, can beused. Derivatives of drugs, such as bases, esters and amides also can beused as a therapeutic agent. A therapeutic agent that is water insolublecan be used in a form that is a water soluble derivative thereof, or asa base derivative thereof, which in either instance, or by its delivery,is converted by enzymes, hydrolyzed by the body pH, or by othermetabolic processes to the original therapeutically active form.

The therapeutic agent can be a chemotherapeutic agent, animmunosuppressive agent, a cytokine, a cytotoxic agent, a nucleolyticcompound, a radioactive isotope, a receptor, and a pro-drug activatingenzyme, which may be naturally occurring or produced by synthetic orrecombinant methods, or any combination thereof.

Drugs that are affected by classical multidrug resistance, such as vincaalkaloids (e.g., vinblastine and vincristine), the anthracyclines (e.g.,doxorubicin and daunorubicin), RNA transcription inhibitors (e.g.,actinomycin-D) and microtubule stabilizing drugs (e.g., paclitaxel) canhave particular utility as the therapeutic agent.

A cancer chemotherapy agent is a preferred therapeutic agent. Usefulcancer chemotherapy drugs include nitrogen mustards, nitrosorueas,ethyleneimine, alkane sulfonates, tetrazine, platinum compounds,pyrimidine analogs, purine analogs, antimetabolites, folate analogs,anthracyclines, taxanes, vinca alkaloids, topoisomerase inhibitors andhormonal agents. Exemplary chemotherapy drugs are Actinomycin-D,Alkeran, Ara-C, Anastrozole, Asparaginase, BiCNU, Bicalutamide,Bleomycin, Busulfan, Capecitabine, Carboplatin, Carboplatinum,Carmustine, CCNU, Chlorambucil, Cisplatin, Cladribine, CPT-11,Cyclophosphamide, Cytarabine, Cytosine arabinoside, Cytoxan,Dacarbazine, Dactinomycin, Daunorubicin, Dexrazoxane, Docetaxel,Doxorubicin, DTIC, Epirubicin, Ethyleneimine, Etoposide, Floxuridine,Fludarabine, Fluorouracil, Flutamide, Fotemustine, Gemcitabine,Herceptin, Hexamethylamine, Hydroxyurea, Idarubicin, Ifosfamide,Irinotecan, Lomustine, Mechlorethamine, Melphalan, Mercaptopurine,Methotrexate, Mitomycin, Mitotane, Mitoxantrone, Oxaliplatin,Paclitaxel, Pamidronate, Pentostatin, Plicamycin, Procarbazine,Rituximab, Steroids, Streptozocin, STI-571, Streptozocin, Tamoxifen,Temozolomide, Teniposide, Tetrazine, Thioguanine, Thiotepa, Tomudex,Topotecan, Treosulphan, Trimetrexate, Vinblastine, Vincristine,Vindesine, Vinorelbine, VP-16, and Xeloda.

Useful cancer chemotherapy drugs also include alkylating agents such asThiotepa and cyclosphosphamide; alkyl sulfonates such as Busulfan,Improsulfan and Piposulfan; aziridines such as Benzodopa, Carboquone,Meturedopa, and Uredopa; ethylenimines and methylamelamines includingaltretamine, triethylenemelamine, trietylenephosphoramide,triethylenethiophosphaoramide and trimethylolomelamine; nitrogenmustards such as Chlorambucil, Chlornaphazine, Cholophosphamide,Estramustine, Ifosfamide, mechlorethamine, mechlorethamine oxidehydrochloride, Melphalan, Novembiehin, Phenesterine, Prednimustine,Trofosfamide, uracil mustard; nitroureas such as Cannustine,Chlorozotocin, Fotemustine, Lomustine, Nimustine, and Ranimustine;antibiotics such as Aclacinomysins, Actinomycin, Authramycin, Azaserine,Bleomycins, Cactinomycin, Calicheamicin, Carabicin, Carminomycin,Carzinophilin, Chromoinycins, Dactinomycin, Daunorubicin, Detorubicin,6-diazo-5-oxo-L-norleucine, Doxorubicin, Epirubicin, Esorubicin,Idambicin, Marcellomycin, Mitomycins, mycophenolic acid, Nogalamycin,Olivomycins, Peplomycin, Potfiromycin, Puromycin, Quelamycin,Rodorubicin, Streptonigrin, Streptozocin, Tubercidin, Ubenimex,Zinostatin, and Zorubicin; anti-metabolites such as Methotrexate and5-fluorouracil (5-FU); folic acid analogues such as Denopterin,Methotrexate, Pteropterin, and Trimetrexate; purine analogs such asFludarabine, 6-mercaptopurine, Thiamiprine, and Thioguanine; pyrimidineanalogs such as Ancitabine, Azacitidine, 6-azauridine, Carmofur,Cytarabine, Dideoxyuridine, Doxifluridine, Enocitabine, Floxuridine, and5-FU; androgens such as Calusterone, Dromostanolone Propionate,Epitiostanol, Rnepitiostane, and Testolactone; anti-adrenals such asaminoglutethimide, Mitotane, and Trilostane; folic acid replenisher suchas frolinic acid; aceglatone; aldophosphamide glycoside; aminolevulinicacid; Amsacrine; Bestrabucil; Bisantrene; Edatraxate; Defofamine;Demecolcine; Diaziquone; Elfornithine; elliptinium acetate; Etoglucid;gallium nitrate; hydroxyurea; Lentinan; Lonidamine; Mitoguazone;Mitoxantrone; Mopidamol; Nitracrine; Pentostatin; Phenamet; Pirarubicin;podophyllinic acid; 2-ethyihydrazide; Procarbazine; PSK®; Razoxane;Sizofrran; Spirogermanium; tenuazonic acid; triaziquone;2,2′,2″-trichlorotriethylamine; Urethan; Vindesine; Dacarbazine;Mannomustine; Mitobronitol; Mitolactol; Pipobroman; Gacytosine;Arabinoside (“Ara-C”); cyclophosphamide; thiotEPa; taxoids, e.g.,Paclitaxel (TAXOL®, Bristol-Myers Squibb Oncology, Princeton, N.J.) andDoxetaxel (TAXOTERE®, Rhone-Poulenc Rorer, Antony, France);Chlorambucil; Gemcitabine; 6-thioguanine; Mercaptopurine; Methotrexate;platinum analogs such as Cisplatin and Carboplatin; Vinblastine;platinum; etoposide (VP-16); Ifosfamide; Mitomycin C; Mitoxantrone;Vincristine; Vinorelbine; Navelbine; Novantrone; Teniposide; Daunomycin;Aminopterin; Xeloda; Ibandronate; CPT-11; topoisomerase inhibitor RFS2000; difluoromethylornithine (DMFO); retinoic acid; Esperamicins;Capecitabine; and pharmaceutically acceptable salts, acids orderivatives of any of the above. Also included are anti-hormonal agentsthat act to regulate or inhibit hormone action on tumors such asanti-estrogens including for example Tamoxifen, Raloxifene, aromataseinhibiting 4(5)-imidazoles, 4 Hydroxytamoxifen, Trioxifene, Keoxifene,Onapristone, And Toremifene (Fareston); and anti-androgens such asFlutamide, Nilutamide, Bicalutamide, Leuprolide, and Goserelin; andpharmaceutically acceptable salts, acids or derivatives of any of theabove.

Cytokines can be also used as the therapeutic agent. Examples of suchcytokines are lymphokines, monokines, and traditional polypeptidehormones. Included among the cytokines are growth hormones such as humangrowth hormone, N-methionyl human growth hormone, and bovine growthhormone; parathyroid hormone; thyroxine; insulin; proinsulin; relaxin;prorelaxin; glycoprotein hormones such as follicle stimulating hormone(FSH), thyroid stimulating hormone (TSH), and luteinizing hormone (LH);hepatic growth factor; fibroblast growth factor; prolactin; placentallactogen; tumor necrosis factor-α and -β; mullerian-inhibitingsubstance; mouse gonadotropin-associated peptide; inhibin; activin;vascular endothelial growth factor; integrin; thrombopoietin (TPO);nerve growth factors such as NGF-β; platelet growth factor; transforminggrowth factors (TGFs) such as TGF-α and TGF-β; insulin-like growthfactor-I and -II; erythropoietin (EPO); osteoinductive factors;interferons such as interferon-α, -62 and -γ; colony stimulating factors(CSFs) such as macrophage-CSF (M-CSF); granulocyte-macrophage-CSF(GM-CSF); and granulocyte-CSF (GCSF); interleukins (ILs) such as IL-1,IL-1a, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-11, IL-12,IL-15; a tumor necrosis factor such as TNF-α or TNF-β; and otherpolypeptide factors including LIF and kit ligand (KL). As used herein,the tern cytokine includes proteins from natural sources or fromrecombinant cell culture and biologically active equivalents of thenative sequence cytokines.

The imaging agent can be any substance that can provide imaginginformation about a targeted site in a body of an animal such a mammalor a human being. The imaging agent can comprise magnetic material, suchas iron oxide, for magnetic resonance imaging. For optical imaging, theactive agent can be, for example, semiconductor nanocrystal or quantumdot. For optical coherence tomography imaging, the imaging agent can bemetal, e.g. gold or silver, nanocage particles. The imaging agent can bealso an ultrasound contrast agent such as a micro or nanobubble or ironoxide micro or nanoparticle.

Compositions

The particles can be part of a composition such as a pharmaceuticalcomposition. Such a composition can be a suspension comprising theselected particles described above for use in administering atherapeutic or imaging agent. To form the suspension, the particles canbe suspended in an aqueous medium at a selected concentration. Theoptimal concentration will depend on the characteristics (e.g.,solubilization properties) of the particle, type of therapeuticapplication and mode of administration. For example, compositions fororal administration can be relatively viscous, and may therefore containa high concentration (e.g., >50%) of the particle. Solutions for bolusinjections preferably contain a relatively concentrated suspension ofthe particles (e.g., 10-50%), but not so concentrated that it has anappreciably higher viscosity than saline (to minimize need forlarge-bore needles). The solution used for continuous intravenousinfusion typically contains a relatively low concentration (e.g., 2-10%suspension) of the particles, due to the relatively large volumes offluid that are administered.

The particles can be suspended in any suitable aqueous carrier vehicle.A suitable pharmaceutical carrier is one that is non-toxic to therecipient at the dosages and concentrations employed and is compatiblewith other ingredients in the formulation. Examples of suitable carriervehicles include but are not limited to water, saline, Ringer'ssolution, dextrose solution, and 5% human serum albumin. Suspensions foruse in injectable formulations are preferably isotonic with thesubject's blood. Generally, the carrier can contain minor amounts ofadditives such as substances that enhance isotonicity and chemicalstability, e.g., buffers and preservatives, as well as low molecularweight (less than about 10 residues) polypeptides, proteins, aminoacids, carbohydrates including glucose or dextrans, chelating agentssuch as EDTA, or other excipients.

Prior to administration to a subject, the suspension of particles can besterilized by a suitable sterilization method. Particles fabricated froma heat-stable material can be heat-sterilized, e.g., using an autoclave.Particles fabricated from a not heat-stable material may be sterilizedby passage through a commercially-available sterilization filter, e.g.,a 0.2 μm filter. Of course, filtration may be used only in cases wherethe particles is smaller than the pores of the sterilizing filter.

The particles can be administered to a subject in need of therapeuticintervention via any suitable administration method. The particularmethod employed for a specific application is determined by theattending physician. The particles can be administered by one of thefollowing routes: topical, parenteral, inhalation, oral, vaginal andanal. Intravascular administration, which includes intravenous (i.v.),intramuscular (i.m.) and subcutaneous (s.c.) injection, may beparticularly preferred.

Intravascular administration can be either local or systemic. Localintravascular delivery can be used to bring the particles in thevicinity of a body site having a known tumor or inflammation by use ofguided catheter system, such as a CAT-scan guided catheter. Generalinjection, such as a bolus i.v. injection or continuous/trickle-feedi.v. infusion are typically systemic.

The selected particles are injected into the blood stream and allowed tocirculate and localize to their target site. Preferably, the selectedparticles are injected to a vasculature of a body site for which theparticles are selected to provide enhanced delivery into fenestratedblood vessels of the body site.

Although the foregoing description refers to particular preferredembodiments, it will be understood that the present invention is not solimited. It will occur to those of ordinary skill in the art thatvarious modifications may be made to the disclosed embodiments and thatsuch modifications are intended to be within the scope of the presentinvention. All of the publications, patent applications and patentscited in this specification are incorporated herein by reference to theextent that they describe materials, methods and other details that aresupplementary to the disclosure herein.

1. A method for targeting a fenestrated blood vessel in a body site,comprising administering to a subject in need thereof a compositioncomprising particles having a radius that permits enhanced delivery intothe fenestrated blood vessel of the body site, wherein the particlescomprise at least one active agent.
 2. The method of claim 1, whereinthe at least one active agent comprises a therapeutic agent.
 3. Themethod of claim 2, wherein the therapeutic agent is an anticancer agent.4. The method of claim 1, wherein the active agent comprises an imagingagent.
 5. The method of claim 1, wherein the particles comprise ananoporous material.
 6. The method of claim 5, wherein the nanoporousmaterial is a nanoporous silicon.
 7. The method of claim 5, wherein thenanoporous material is a nanoporous oxide material.
 8. The method ofclaim 7, wherein the nanoporous oxide material is a nanoporous silicondioxide.
 9. The method of claim 1, wherein one or more of said particlescomprise a biodegradable material.
 10. The method of claim 1, whereinone or more of said particles comprise at least one recognition moietydisposed on a surface of each of the particles.
 11. The method of claim10, wherein the at least one recognition moiety comprises a renormalizedvasculature recognition moiety.
 12. The method of claim 10, wherein theat least one recognition moiety comprises a coopted vasculaturerecognition moiety.
 13. The method of claim 10, wherein the at least onerecognition moiety comprises an angiogenesis vasculature recognitionmoiety.
 14. The method of claim 10, wherein the at least one recognitionmoiety comprises hydrophilic polymer chains.
 15. The method of claim 1,wherein one or more of said particles are selected from the groupconsisting of liposomes, fullerene nanoparticles, semiconductornanoparticles and metal nanoparticles.
 16. The method of claim 1,further comprising fabricating the one or more particles.
 17. The methodof claim 15, wherein the fabricating comprises fabricating by a top-downtechnique.
 18. The method of claim 1, wherein the administeringcomprises injecting the composition intravascularly.
 19. The method ofclaim 18, wherein the injecting comprises injecting the composition in avasculature of the body site.
 20. The method of claim 1, wherein thesubject is a mammal.
 21. The method of claim 20, wherein the subject isa human.
 22. The method of claim 1, wherein the body site is selectedfrom the group consisting of brain, skin, skeletal muscle, lung, heart,kidney, stomach and intestine.
 23. The method of claim 1, wherein thecomposition comprises a suspension of the particles.
 24. The method ofclaim 1, wherein a condition responsible for the fenestrated bloodvessel condition is a tumor.
 25. The method of claim 1, furthercomprising administering to the subject a vasculature normalizing agent.26. A method of improving efficacy of a composition comprising particlesthat comprise at least one active agent, the method comprising selectingparticles from a first population of micro or nanoparticles, such thatthe particles have a radius that permits enhanced delivery intofenestrated blood vessels of a target body site and forming acomposition comprising the selected particles.
 27. The method of claim26, wherein the selected particles constitute at least 10% of the firstparticles by number.
 28. The method of claim 27, wherein the selectedparticles constitute at least 20% of the first particles by number. 29.The method of claim 28, wherein the selected particles constitute atleast 50% of the first particles by number.
 30. The method of claim 29,wherein the selected particles constitute at least 80% of the firstparticles by number.